PHILADELPHIA, the United States, April 15 (Xinhua) -- Starbucks' chief executive apologized in a press release Sunday for a recent racist arrest in one of the coffee stores, which triggered demonstration on the street and condemnation on social media.

Two black men Thursday went to a business meeting in a Starbuck store in Philadelphia, Pennsylvania, but were arrested because they did not order a drink.

Philadelphia's Police Commissioner Richard Ross confirmed Starbucks employees called 911 and said two black men were trespassing; as they refused to leave, they were arrested and eventually released eight hours later.

A social media user Melissa Depino tweeted "the police were called because these men hadn't ordered anything. They were waiting for a friend to show up ... All the other white ppl (people) are wondering why it's never happened to up when we do the same thing."

The user also posted a video of part of the incident, which sparked outrage at the controversial and racist arrest.

Starbucks Chief Executive Official Kevin Johnson on Sunday expressed his "apologies to the two men who were arrested" and said "Starbucks stands firmly against discrimination or racial profiling," describing the incident as "a disheartening situation" and the arrest as "a reprehensible outcome."

Johnson also said the company "has immediately begun a thorough investigation of our (employees') practices," adding Starbuck will work with outside experts and community leaders to understand and improve their practices.

More than three-dozen protestors rallied on Sunday afternoon outside the concerned store, demanding firing of the store manager.

Philadelphia Mayor Jim Kenney said Saturday "I'm heartbroken to see Philadelphia in the headlines for an incident that ... appears to exemplify what racial discrimination look like in 2018," local media reported.